Compressor lubricant equalizing pump



March 22, 1966 D. N. SHAW 3,241,746

COMPRESSOR LUBRICANT EQUALIZING PUMP Filed Feb. 8, 1965 2 Sheets-Sheet 1FIG. I

INVENTOR.

DAVID N. SHAW.

ATTORNEY.

March 22, 1966 D. N. SHAW 3,241,746

COMPRESSOR LUBRICANT EQUALIZING PUMP Filed Feb. 8, 1965 2 Sheets-Sheet 2IN VEN TOR.

DAVID N. SHAW.

ATTORNEY.

United States Patent 3,241,746 COMPRESSOR LUBRICANT EQUALIZING PUMPDavid N. Shaw, Liverpool, N.Y., assignor to Carrier Corporation,Syracuse, N.Y., a corporation of Delaware Filed Feb. 8, 1965, Ser. No.431,115 6 Claims. (Cl. 230206) This invention relates to compressors,and more particularly, to a lubrication arrangement for compressorsadapted for use in multiple compressor systems.

In systems employing multiple compressors, excess lubricant mayaccumulate in one or more of the compressors at the expense of theremaining compressor or compressors. This occurrence is particularly inevidence Where one of the compressors has, or by means of an unloadermechanism is, operated at a capacity different from that of theremaining compressor or compressors, or Where one or more of thecompressors is shutdown while the remaining compressor or compressors isused to sustain system operation at reduced capacity. Variations inpressure conditions within the crankcase compartments of the severalcompressors may override the lubricant balancing function of equalizinglines interconnecting the crankcase compartments of the severalcompressors resulting in excess lubricant in the crankcase compartmentof one compressor to the detriment of the remaining compressor orcompressors.

It is a principal object of the present invention to provide a new andimproved arrangement for insuring adequate quantities of lubricant ineach compressor of a multiple compressor system.

It is a further object of the present invention to provide an oilequalizing arrangement which prevents lubricant starvation of onecompressor in multiple compressor installations.

It is an object of the present invention to provide pumping apparatusfor withdrawing excess lubricant from one compressor for transfer toanother compressor of a multiple compressor installation.

It is an object of the present invention to provide an auxiliary pumpfor use with compressors adapted for multiple compressor installations,the auxiliary pump being driven from the compressor and being operableto remove excess oil from the sump of the compressor.

This invention relates to a sytem having at least two compressors, eachcompressor including a sump for the storage of lubricant comprising incombination means for withdrawing excess lubricant from the sump of afirst of the compressors including a member having a chamber therein; apiston-like operator movably disposed in the chamber, the operatorseparating the chamber into first and second compartments; the memberhaving first and second passages therein opening into the firstcompartment, the first passage being connected to the first compressorsump at a predetermined lubricant level; means regulating that firstpassage to prevent outflow of lubricant from the first compartmentthrough the first passage into the first compressor sump; control meansadapted to communicate the second compartment with a source ofpressurized fluid to move the operator to force lubricant in the firstcompartment through the second passage; and means connecting the secondpassage with the sump of a second of the compressors.

This invention further relates to a lubricant transfer means for usewith a compressor of the type having a sump for storage of lubricant andmeans for distributing the lubricant to the working parts thereof, thecompressor being adapted for use in multiple compressor installations,the lubricant transfer means comprising in combination a member having acavity therein; a piston movably disposed in the member cavity, thepiston separating the cavity into motor and pumping compartments; themem- 3,241,746 Patented Mar. 22, 1966 her having suction and dischargepassageways opening into the pumping compartment, the suction passagewaybeing connectable to the compressor sump at a selected lubricant level;means for closing the suction passageway to the discharge of lubricant;a first passage connecting the drive compartment to the discharge sideof the compressor lubricant distributing means to move the piston anddrive lubricant through the pumping compartment discharge passageway;bias means for retracting the piston; a second passage adapted toconnect the drive compartment with the compressor sump; and controlmeans for interrupting the first passage while opening the secondpassage in response to predetermined movement of the piston whereby thebias means retracts the piston.

Other objects will be apparent from the ensuing description and drawingsin which:

FIGURE 1 is a view partly in section and partly in elevation of amultiple compressor arrangement incorporating the improved lubricationsystem; and

FIGURE 2 is an enlarged view in section showing the equalizing pumpapparatus of the present invention.

Referring to FIGURE 1 of the drawings, there is shown a multiplecompressor installation incorporating my improved lubrication system andhaving parallel connected compressors 2. According to a preferredconstruction, each compressor 2 includes a shell or housing 4 partionedinto a motor compartment 7 having drive motor 8 therein and crankcasecompartment 9 having compression means 10 therein. Crankshaft 11operably interconnects rotor 8 of motor 8 with compression means 10.

Compressors 2 are shown as hermetic type compressors wherein gas fromsuction header 19 passes through conduits 13 into the motor compartment7 of each compressor and into heat exchange relation with the drivemotor 8 thereof to cool the motor, the suction gas thereafter passingthrough the intake manifold 16 to'compression means 10. Compressionmeans 10 discharges relatively high pressure gas through the dischargemanifold 17 of each compressor 2 into conduits 12 and discharge header18. Headers 18, 19 connect compressors 2 with the high and low pressuresides of a closed refrigeration system.

The lower part of each compressor crankcase com partment 9 serves as asump or reservoir 20 for lubricant. Suitable pump mechanisms, designatedgenerally by numeral 22, distribute lubricant drawn from sumps 20 to thevarious points of frictional wear throughout compressors 2 such ascrankshaft bearing 23. Pump mechanisms 22 are drivingly connected tocrankshafts 11 in a manner known to those skilled in the art.

Compressors 2 are each provided with an auxiliary pump, designatedgenerally by the numeral 25, which will be more particularly describedhereinafter. Conduits 24 connect the crankcase compartment sump of eachcompressor 2 with the discharge side of the auxiliary pump as sociatedwith the other compressor. The suction sides of pump 25 are connected totheir associated compressor sumps at a desired lubricant level. A smallline 29 interconnects the sumps 20 of compressors 2. Line 29 isconnected to the compressor sumps slightly above the normal lubricantlevel. Line 29 functions to prevent the accumulation of excess lubricantin the off compressor.

Referring to FIGURE 2 of the drawings, each auxiliary pump 25 comprisesa pump body 26 suitably secured to compressor housing 4 as by bolts 27opposite crankcase opening 28. Opening 30 in pump body 26 has movablepiston 31 disposed therein. Opening 30 is reduced in diameter at 32 todefine a generally cylindrical stop surface which limits movement ofpiston 31 in one direction.

A hollow generally cylindrical member 35 is sealingly secured within oneend of opening 30. Opening 38 in member 35 communicates the pumpingside, space 37,

3 with conduit 24. Ball-type check valve 39 biased toward closedposition by spring 40 prevents reverse flow of lubricant from conduit 24through opening 38 into space 37.

The leading edge of member 35 forms a stop surface 41 which limitsmovement of piston 31 in the opposite direction. Spring 42 biases piston31 in the direction of stop surface 32.

The opposite end of pump body opening 30 is closed by end plate 43sealingly attached to pump body 26 as by bolts 44. A passage 45communicates the motor side of pump 25, space 46, with a source ofpressurized fluid as for example the discharge side of compressorlubricant pump 22. Passage 4S communicates space 46 with a suitable lowpressure area as for example compressor sump 20. A generally cylindricalmovable valve member 50 controls communication of passages 45, 48 withspace 46. The external surface of valve member 50 is recessed at 51, 52.Detent ball 53, biased into engagement with valve member 50 by spring54, cooperates with recess 51 or 52 to releasably retain valve member 50in a position where passage 45 communicates with space 46, asillustrated in FIGURE 2 of the drawings, or in a position where passage48 communicates with space 46.

Piston 31 has a stem 57 protruding into space 46. Spring 59 is disposedbetween abutment 58 on stem 57 and valve member 50.

Passage 60 in valve body 26 communicates space 37 with sump of thecompressor to which equalizing ump is appended. Ball-type check valve61, biased toward closed position by spring 62, prevents reverse flow oflubricant from space 37 into the compressor sump.

With piston 31 and control valve 50 of the auxiliary pump in theposition illustrated in FIGURE 2 of the drawings and excess lubricantfrom the compressor sump in space 37, the admission of relatively highpressure lubricant to space 46 forces piston 31 to the right as seen inFIGURE 2 against the bias of spring 42. Check valve 61 prevents outflowof lubricant through passage 60 from space 37. Lubricant trapped inspace 37 is forced by piston 31 through conduit 24 into sump 20 of theother compressor.

As abutment 58 on stem 57 approaches valve member 50, the forcenecessary to move piston 31 increases. Pressure in space 46correspondingly increases thereby sustaining movement of piston 31 andlifting detent ball 53 out of recess 51. As ball 53 rises, the forcerequired to continue lifting movement of ball 53 decreases. Theincreased pressure in space 46 compounded by the energy accumulated inspring 59 snaps valve member 50 to the right as seen in FIGURE 2interrupting passage and uncovering vent passage 48. Detent ball 53cooperates with recess 52 to hold valve member in the vent position.

With space 46 vented to a low pressure source, such as compressor sump20, spring 42 retracts piston 31. As piston 31 retracts, lubricant isdrawn through passage into space 37. Check valve 39 closes opening 38 toprevent inflow of lubricant from the other compressor sump into space37. As piston 31, under the influence of spring 42 approaches stop 32,piston 31 moves valve member 59 to interrupt vent passage 48 and uncoverpressure passage 45 to once again drive the piston 31 to the right asseen in FIGURE 2. It is understood that auxiliary pump 25 operates solong as the source of fluid pressure is available. Where the source offluid pressure comprises the compressor oil pump 22, the operation ofauxiliary pump 25 is contingent upon operation of the compressor.

Where the lubricant level in the sump of the com pressor, duringoperation of the compressor, is below the level of opening 28, it isunderstood that the equalizing pump 25 associated therewith, althoughoperational, does not effect transfer of lubricant into the sump of theother compressor. The operation of the equalizing pump associated withthe other compressor is similar to that described herebefore.

Where one of the compressors 2 is idle, the equalizing pump 25associated with that compressor is inoperative. During operation of thesystem with one compressor, lubricant may accumulate or trap in the sumpof the idle compressor. Line 29 permits excess lubricant in the sump ofthe idle compressor to return to the sump of the othercompressor. It isunderstood that pressure in the crankcase compartment of the idlecompressor is normally greater than pressure in the crankcasecompartment of the operating compressor. Thus, lubricant in the idlecompressor at or above the level of line 29 is forced through line 29into the sump of the other compressor. The size of line 29 is such thatline 29 is normally incapable of equalizing pressures in the crankcasecompartments of the compressor 2.

The relatively small sized line 29 between the sumps of the compressors2, which prevents the accumulation of excess lubricant in the sump ofone compressor when that compressor is idle, may be dispensed with ifdischarge and suction lines 12, 13 respectively are suitably designed toprevent trapping of lubricant in the 011 compressor during operation ofthe other compressor. Lubricant trapping may be obviated if thedischarge and suction lines 12, 13 are arranged so that the juncturethereof with discharge and suction headers 18, 19 respectively is belowthe junction of discharge and suction lines 12, 13 with compressors 2.In effect this arrangement requires that suction gas flowing into thecompressors flow upwardly while gas discharged from the compressors flowdownwardly.

While I have described a preferred embodiment of my invention, it willbe understood that my invention is not limited thereto since it may beotherwise embodied within the scope of the following claims.

I claim:

1. In a system having at least two compressors, each compressorincluding a sump for the storage of lubricant, the combination of meansfor withdrawing excess lubricant from the sump of a first of saidcompressors including a member having a chamber there-in; a piston-likeoperator movably disposed in said chamber, said operator separating saidchamber into first and second compartments; said member having first andsecond passages therein opening into said first compartment, sa-id firstpassage being connected to said first compressor sump at a predeterminedlubricant level; means regulating said first passage to prevent outflowof lubricant from said first compartment through said first passage intosaid first compressor sump; control means adapted to communicate saidsecond compartment with a source of pressurized fluid to move saidoperator to force lubricant in said first compartment through saidsecond passage; and means connecting said second passage with the sumpof a second of said compressors.

2. The system according to claim 1 including bias means for retractingsaid piston-like operator, said cont-r01 means being operable uponpredetermined movement of said piston-like operator to reduce pressurein said second compartment to permit said bias means to retract saidpistonlike operator.

3. The system according to claim 2 in which said second passageconnecting means includes means regulating said second passage toprevent inflow of lubricant from said second compressor sump throughsaid second passage into said first compartment.

4. The system according to claim 3 in which said first compressorincludes lubricant pumping means having suction and discharge sides,said control means communicating said second compartment with thedischarge side of said pumping means to apply pressurized lubricant tosaid piston-like operator.

5. The system according to claim 3 including a second member having achamber therein, a piston-like operator movably disposed in said secondmember cham ber, said operator separating said second member chama herinto first and second compartments, said second member having first andsecond passages therein opening into Said first compartment, said secondmember first passage being connected to said second compressor sump at apredetermined lubricant level, means regulating said second member firstpassage to prevent outflow of lubricant from said second member firstcompartment through said first passage thereof into said secondcompressor sump, control means adapted to communicate said second membersecond compartment with a source of pressurized fluid to move saidoperator to force lubricant in said second member first compartmentthrough said second member second passage, and means connecting saidsecond member second passage with said first compressor sump, saidlast-mentioned means including means regulating said second membersecond passage to prevent inflow of lubricant from said first compressorsump through said second member second passage into said second memberfirst compartment.

6. Lubricant transfer means for use with a compressor of the type havinga sump for storage of lubricant and means for distributing saidlubricant to the working parts thereof, said compressor being adaptedfor use in multiple compressor installations, the combination of amember having a cavity therein; a piston movably disposed in said membercavity, said piston separating said cavity into motor and pumpingcompartments; said member having suction and discharge passagewaysopening into said pumping compartment, said suction passageway beingconnectable to said compressor sump at a selected lubricant level; meansfor closing said suction passageway to the discharge of lubricant; afirst passage connecting said drive compartment to the discharge side ofsaid compressor lubricant distributing means to move said piston anddrive lubricant through said pumping compartment discharge passageway;bias means for retracting said piston; a second passage adapted toconnect said drive compartment with said compressor sump; and controlmeans for interrupting said first passage while opening said secondpassage in response to predetermined movement of said piston wherebysaid bias means retracts said piston.

References Cited by the Examiner UNITED STATES PATENTS 3,009,632 11/1961Berger et a1. 230-206 3,072,318 1/1963 Berger et al. 230206 ROBERT M.WALKER, Primary Examiner.

1. IN A SYSTEM HAVING AT LEAST TWO COMPRESSORS, EACH COMPRESSORINCLUDING A SUMP FOR THE STORAGE OF LUBRICANT, THE COMBINATION OF MEANSFOR WITHDRAWING EXCESS LUBRICANT FROM THE SUMP OF A FIRST OF SAIDCOMPRESSORS INCLUDING A MEMBER HAVING A CHAMBER THEREIN; A PISTON-LIKEOPERATOR MOVABLY DISPOSED IN SAID CHAMBER, SAID OPERATOR SEPARATING SAIDCHAMBER INTO FIRST AND SECOND COMPARTMENTS; SAID MEMBER HAVING FIRST ANDSECOND PASSAGES THEREIN OPENING INTO SAID FIRST COMPARTMENT, SAID FIRSTPASSAGE BEING CONNECTED TO SAID FIRST COMPRESSOR SUMP AT A PREDETERMINEDLUBRICANT LEVEL; MEANS REGULATING SAID FIRST PASSAGE TO PREVENT OUTFLOWOF LUBRICANT FROM SAID FIRST COMPARTMENT THROUGH SAID FIRST PASSAGE INTOSAID FIRST COMPRESSOR SUMP; CONTROL MEANS ADAPTED TO COMMUNICATE SAIDSECOND COMPARTMENT WITH A SOURCE OF PRESSURIZED FLUID TO MOVE SAIDOPERATOR TO FORCE LUBRICANT IN SAID FIRST COMPARTMENT THROUGH SAIDSECOND PASSAGE; AND MEANS CONNECTING SAID SECOND PASSAGE WITH THE SUMPOF A SECOND OF SAID COMPRESSORS.